1. Field of the Invention
The present invention relates to an endoscope system having an auxiliary lighting device which lights up in the event of failure in a main light source of the endoscope.
2. Description of the Related Art
In an endoscope system having an auxiliary lighting device, the incident end face of a fiber-optic light guide (a bundle of fibers) of the endoscope is connected to the lighting device. The incident end face of the fiber-optic light guide is positioned to face a main lamp provided in the lighting device, while the exit end face of the fiber-optic light guide is connected to an illumination lens provided at the insertion end of the flexible insertion tube of the endoscope. Illuminating light emitted from the main lamp is guided to the illumination lens through the fiber-optic light guide to be projected outwards from the illumination lens to illuminate an internal body cavity, or an internal cavity inside a machine. This structure is disclosed in, e.g., a Japanese laid-open patent publication NO.11-305148.
If the lighting device is provided with only one lamp, an endoscopic operation must be suspended in the event where the lamp goes out accidentally during the endoscopic operation. To prevent this problem from occurring, the lighting device is usually provided with an auxiliary lamp which lights up in the event of failure in the main lamp. The auxiliary lamp is retracted so as not to face the incident end face of the fiber-optic light guide in a normal state of the endoscope. In the event of accidental failure of the main lamp, the auxiliary lamp moves to its operating position, at which the auxiliary lamp faces the incident end face of the fiber-optic light guide, and lights up to supply illuminating light to the incident end face of the fiber-optic light guide.
However, in conventional endoscopes having such an auxiliary lamp, the service life of the auxiliary lamp is short consumes a large amount of power because a light source such as an xenon lamp which consumes a high amount of power is used as the auxiliary lamp.